In the early days of computing, information was generally encoded as formatted alphanumeric character strings or as unformatted ordered sequences of information-storage units, typically bytes. As computing hardware, operating systems, and computer applications have together evolved, many different types of information encodings have been developed, and a very large variety of different types of information are now routinely electronically encoded, stored, exchanged, and rendered for access by users, including text files, specially formatted application-specific files, audio recordings, video recordings, and multimedia presentations. While, in early days of computing, data was primarily rendered as character strings displayed on monochromatic, 24-line terminals, the many different types of information currently electronically encoded and distributed by computer systems are rendered for presentation to human users by a variety of different application programs, including text and image editors, video players, audio players, and web browsers.
An important class of information comprises information encoded as an ordered sequence of information units that are sequentially rendered for display or presentation to a human user. An MPEG-encoded video file is one example of a sequentially ordered information encoding. MPEG encoding employs a number of rather complex layers of different types of encoding methods compactly encode a video stream and/or audio stream. In general, video frames are reconstructed from an MPEG-encoded video file frame-by-frame, in sequence. Rendering of an MPEG-encoded video file provides a stream of video frames and an audio stream. Rendering applications and devices generally allow a user to start or resume rendering of the video file, to stop rendering of the video file, and to skip forward or backward to selected positions within a video stream.
In many cases, a user may only be interested in a certain portion of a video presentation. For example, a particular user may be interested only in a weather report included in a local television news broadcast that includes reviews of current local and national events, reviews of sporting events, and presentations of human-interest stories in addition to the weather report. In many cases, video presentations may not be indexed by sections, in order to facilitate direct access to portions of the video presentation of interest to a user, or may be indexed at a very coarse topic granularity, requiring a user to employ a hit-or-miss strategy of starting, stopping, advancing, and reversing the video stream by relatively crude techniques in order to locate portions of interest. In addition to encoded video, there are many other types of sequentially ordered information encodings that are sequentially rendered for human perception, including pure audio recordings, various types of multimedia presentations, images of pages within books and text documents, and other such information encodings. In many cases, searching for portions of the encoded information of interest to human users is currently limited to the above-described stop/start/advance/and reverse operations familiar to users of video-rendering applications and many video-signal-rendering devices. Designers and manufacturers of computers and other electronic devices that render sequentially ordered information encodings for presentation to human users, designers, implementers, vendors and users of information-rendering applications, including media players, web browsers, and control programs, and many others involved in recording, disseminating, and rendering information have recognized the need for more effective searching tools to allow users to identify and efficiently access portions of an information encoding of interest to those to whom the information is rendered.